The Program Project (Pennsylvania Muscle Institute) functions as a multi- institutional, interdisciplinary program for collaborative studies on normal and diseased cardiac and skeletal muscle and blood platelets. The major theme of the Program is the assembly and mechano-chemistry of contractile proteins. It integrates investigations of contractile proteins from genetic regulation of cell differentiation, development, isoform diversity and growth, assembly of the components in vitro, myofibrillogenesis in live, differentiating cells and the molecular motions and reaction kinetics in fully constituted myofibrils. The objective is to understand how contractile proteins form highly specific, functional macromolecular assemblies in vitro and in vivo and, how these complex assemblies perform their task of chemical-to-mechanical energy transduction at the molecular level. The projects and investigators within the Program are interdependent and closely linked through complimentary research goals and shared technologies, resources and training programs. Novel instrumentation to be developed for the research will include microscopically localized photolysis of photolabile ("caged") precursors of fluorescent labels for dynamic studies of incorporation and exchange of contractile proteins, time-resolved and scanning confocal fluorescence polarization microscopy and ultra-rapid freezing electron microscopy synchronized to transient molecular events initiated by laser pulse photolysis of "caged" substrate or signal molecules. Novel techniques will include new eukaryotic co-expression systems for protein structure-function studies, transfection and micro- injection of cDNA plasmids coding for truncated, mutated or chimeric proteins into primary cultured myocytes, and mass spectrometry of nanomolar stable phosphate isotopes. The long-term scientific aims and technologies developed in the Program Project are directed to understanding the normal growth, assembly and function as well as pathophysiology of muscles relevant to the cardiovascular and pulmonary systems.